FIG. 1 illustrates a schematic diagram showing architecture of System Architecture Evolution (SAE). In FIG. 1, user equipment (UE) 101 is a terminal device used for receiving data. Evolved universal terrestrial radio access network (E-UTRAN) 102 is a radio access network, which includes a macro base station (eNB) who provides a wireless network interface for the UE. Mobility management entity (MME) 103 is responsible for managing mobile contexts, session contexts and security information of the UE. Service gate way (SGW) 104 primarily provides a function of a user plane. MME 103 and SGW 104 may be in a same physical entity. Packet data network gateway (PGW) 105 is responsible for functions of charging, lawful intercepting, and the like, which may also be in a same physical entity with SGW 104. Policy and charging rule function entity (PCRF) 106 provides quality of service (QoS) policy and charging rules. General packet radio traffic support node (SGSN) 108 is a network node device that provides a route for data transmission in the universal mobile telecommunications system (UMTS). Home subscriber server (HSS) 109 is a home reverter subsystem of the UE, responsible for protect user information including location of the user equipment, an address of serving node, user security information, packet data context of the user equipment, and the like.
As the rate of the UE traffic data increases, operators provide a new technology referred to as Selected IP Traffic Offload (SIPTO). That is, when the UE accesses a service, the UE handovers to an access point which is closer to the radio access network during its movement, thereby the investment cost of transmission network can be effectively reduced, and a better service experience for the high data rate can be provided.
In 3GPP, a need for the capabilities of the network to support SIPTO and local IP accessing (LIPA) is proposed. There are two architectures for SIPTO in the local network and both of the two architectures can be used not only in H(e)NB but also in eNB.
Architecture I: independent LGW, SGW and LGW are on a same entity. LGW is in a local network. Multiple (H)eNBs may be in one local network. During the service actuation, the (H)eNB sends a local home network ID to which the (H)eNB belongs to a MME. During the movement of the UE, the MME gets to know whether the UE has moved out of the local network according to the identity of the local network received from the (H)eNB in the tracking area update TAU process, thereby can initiate a bearer disconnection process.
Architecture II: As shown in FIG. 2, LGW and (H)eNB are on one entity. The SGW is in the operator's network. This architecture is the same as the architecture of LIPA, and the process of the SIPTO service activation is also the same as that of LIPA. Currently, both SIPTO and LIPA do not support service continuity in the handover process. It may need to release the SIPTO bearer or the LIPA bearer during a handover process. The bearer deactivation process of SIPTO is different from that of LIPA. The bearer deactivation of LIPA is initiated by the source HeNB before the handover. The bearer deactivation of SIPTO is initiated by the source HeNB after the handover.
The prior SIPTO mechanism still have the following problems:
In the embodiment of architecture I, when moving within a same MME, if the UE has not moved out of the TA list, the UE will not initiate a TAU process. Thus as the MME is not aware that the UE has moved out of the local area, the MME will not initiate a bearer disconnection process. In this embodiment, even though the UE has already moved out of the local network, the UE still communicates through LGW of the local network.
In the embodiment of architecture I, when moving between different MMEs, as the source MME is not aware of the local network in which the target base station is located, the source MME does not know whether the UE has moved out of the local network of the source. Thus it is not able to trigger a SIPTO bearer disconnection process.
In the embodiment of architecture I, when moving between different MMEs, the target MME does not know whether the UE moves within the local network, if the UE moves within the local network, the target MME probably may choose a new SGW due to some reasons, for example the load balancing, which causes the traffic on SIPTO bearer not capable of ensuring the continuity. Or when the UE has already moved out of the local network of the source base station, the MME does not select a new SGW for the UE. When moving in the same MME and the selection of SGW is before TAU, if the MME does not know the local network in which the target base station is located before TAU, this problem exists as well.
In the embodiment of architecture II, the bearer deactivation method of SIPTO is different from that of LIPA. The base station does not know the established bearer is LIPA or SIPTO, thus not capable to correctly trigger the deactivation process.